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British Standard Whitworth (B.S.W.)
Thread Form
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- p = Pitch = 1/TPI
- h = Basic Depth of Thread = 0.640327p
- r = Basic Radius = 0.137329p
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Thread Tables
| Nominal Diameter |
T.P.I. |
Basic Depth of Thread |
Basic Major Diameter |
Basic Effective Diameter |
Basic Minor Diameter |
Tapping Drill |
Clearing Drill |
| (inch) |
(n/a) |
(inch) |
(inch) |
(inch) |
(inch) |
(mm) |
(mm) |
| 1/16 |
60 |
0.0107 |
0.0625 |
0.0518 |
0.0411 |
1.2 |
1.65 |
| 3/32 |
48 |
0.0133 |
0.0938 |
0.0805 |
0.0672 |
1.85 |
2.5 |
| 1/8 |
40 |
0.016 |
0.125 |
0.109 |
0.093 |
2.55 |
3.3 |
| 5/32 |
32 |
0.02 |
0.1562 |
0.1362 |
0.1162 |
3.2 |
4.1 |
| 3/16 |
24 |
0.0267 |
0.1875 |
0.1608 |
0.1341 |
3.7 |
4.9 |
| 7/32 |
24 |
0.0267 |
0.2188 |
0.1921 |
0.1654 |
4.5 |
5.7 |
| 1/4 |
20 |
0.032 |
0.25 |
0.218 |
0.186 |
5.1 |
6.5 |
| 5/16 |
18 |
0.0356 |
0.3125 |
0.2769 |
0.2413 |
6.5 |
8.1 |
| 3/8 |
16 |
0.04 |
0.375 |
0.335 |
0.295 |
7.9 |
9.7 |
| 7/16 |
14 |
0.0457 |
0.4375 |
0.3918 |
0.3461 |
9.3 |
11.3 |
| 1/2 |
12 |
0.0534 |
0.5 |
0.4466 |
0.3932 |
10.5 |
13 |
| 9/16 |
12 |
0.0534 |
0.5625 |
0.5091 |
0.4557 |
12.1 |
14.5 |
| 5/8 |
11 |
0.0582 |
0.625 |
0.5668 |
0.5086 |
13.5 |
16.25 |
| 11/16 |
11 |
0.0582 |
0.6875 |
0.6293 |
0.5711 |
15 |
17.75 |
| 3/4 |
10 |
0.064 |
0.75 |
0.686 |
0.622 |
16.25 |
19.25 |
| 13/16 |
10 |
0.064 |
0.8125 |
0.7485 |
0.6845 |
18 |
21 |
| 7/8 |
9 |
0.0711 |
0.875 |
0.8039 |
0.7328 |
19.25 |
22.5 |
| 15/16 |
9 |
0.0711 |
0.9375 |
0.8664 |
0.7953 |
20.75 |
24 |
| 1 |
8 |
0.08 |
1 |
0.92 |
0.84 |
22 |
25.75 |
| 1,1/8 |
7 |
0.0915 |
1.125 |
1.0335 |
0.942 |
24.75 |
29 |
| 1,1/4 |
7 |
0.0915 |
1.25 |
1.1585 |
1.067 |
28 |
32 |
| 1,3/8 |
6 |
0.1067 |
1.375 |
1.2683 |
1.1616 |
30.25 |
35.5 |
| 1,1/2 |
6 |
0.1067 |
1.5 |
1.3933 |
1.2866 |
33.5 |
38.5 |
| 1,5/8 |
5 |
0.1281 |
1.625 |
1.4969 |
1.3688 |
35.5 |
41.5 |
| 1,3/4 |
5 |
0.1281 |
1.75 |
1.6219 |
1.4938 |
39 |
45 |
| 1,7/8 |
4,1/2 |
0.1423 |
1.875 |
1.7327 |
1.5904 |
41.5 |
48 |
| 2 |
4,1/2 |
0.1423 |
2 |
1.8577 |
1.7154 |
44 |
51 |
| 2,1/4 |
4 |
0.1601 |
2.25 |
2.0899 |
1.9298 |
51 |
58 |
| 2,1/2 |
4 |
0.1601 |
2.5 |
2.3399 |
2.1798 |
57 |
64 |
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